1. Field of the Invention
The present invention relates generally to medical methods, systems, and kits. Particularly, the present invention relates to methods and apparatus for performing diagnostic testing on individual subsections or segments of a lung. Further, the present invention provides methods and apparatus for more accurate evaluation of the extent and severity of pulmonary disease in the subsections and segments and the effectiveness of various treatment options.
Chronic obstructive pulmonary disease (COPD) is a significant medical problem affecting 16 million people or about 6% of the U.S. population. Specific diseases in this group include chronic bronchitis, asthmatic bronchitis, and emphysema. In general, two types of diagnostic tests are performed on a patient to determine the extent and severity of COPD: 1) imaging tests and 2) functional tests. Imaging tests, such as chest x-rays, CT scans, MRI, perfusion scans, and bronchograms, provide a good indicator of the location, homogeneity and progression of the diseased tissue. However, these test do not give a direct indication of how the disease is affecting the patient's overall lung function and respiration capabilities. This can be measured with functional testing, such as spirometry, plethysmography, oxygen saturation, and oxygen consumption stress testing, to name a few. Together, these diagnostic tests are used to determine the course of treatment for the patient.
Treatment for emphysema may include a variety of options, one such option is Lung Volume Reduction which typically involves resecting diseased portions of the lung. Resection of diseased portions of the lungs both promotes expansion of the non-diseased regions of the lung and decreases the portion of inhaled air which goes into the lungs but is unable to transfer oxygen to the blood. Lung reduction is conventionally performed in open chest or thoracoscopic procedures where the lung is resected, typically using stapling devices having integral cutting blades. While effective in many cases, conventional lung reduction surgery is significantly traumatic to the patient, even when thoracoscopic procedures are employed. Such procedures often result in the unintentional removal of relatively healthy lung tissue or leaving behind of relatively diseased tissue, and frequently result in air leakage or infection. Consequently, alternative therapies have been developed which utilize minimally invasive techniques to isolate target lung tissue segments from other regions of the lung. Isolation is usually achieved by introducing an access catheter endotracheally or thorascopically to the target air passage of the lung. The target lung tissue segment is then collapsed by aspirating air (and any other gases or liquids that may have been introduced) from the segment and optionally sealed off. Exemplary methods and systems to perform such isolation procedures are described U.S. patent application Ser. No. 09/606,320, incorporated herein by reference.
Currently, the diagnostic tests are limited in the amount and type of information that may be generated. For example, diagnostic imaging may provide information to the physician regarding which lung segments “appear” more diseased, but in fact a segment that appears more diseased may actually function better than one that appears less diseased. Functional testing is performed on the lungs as a whole. Thus, the information provided to the physician is generalized to the whole lung and does not provide information about functionality of individual lung segments. Thus, physicians may find difficulty targeting interventional treatments to the segments most in need and to avoid unnecessarily treating segments that are not in need of treatment or less in need. In general, the diseased segments cannot be differentiated, prioritized for treatment or assessed after treatment for level of response to therapy.
For these reasons, it would be desirable to provide systems, methods, devices and kits which would overcome at least some of the shortcomings discussed above. In particular, it would be desirable to provide systems and methods for monitoring, assessing or measuring the functional state of individual lung compartments; such compartments could be an entire lobe, a segment or a subsegment and beyond, hereinafter subsegments and beyond will be referred to simply as segments. It would be further desirable to provide systems and methods of comparing measured data of individual lung compartments to other individual lung compartments and/or to measured data of the lung as a whole. In addition, it would be desirable to provide systems and methods of estimating or predicting the outcome of treatment options prior to actual treatment and also to assess the state of disease and functionality post-treatment. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Patents and applications relating to lung access, diagnosis, and/or treatment include U.S. Pat. Nos. 6,174,323, 6,083,255, 5,972,026, 5,752,921; 5,707,352; 5,682,880; 5,660,175; 5,653,231; 5,645,519; 5,642,730; 5,598,840; 5,499,625; 5,477,851; 5,361,753; 5,331,947; 5,309,903; 5,285,778; 5,146,916; 5,143,062; 5,056,529; 4,976,710; 4,955,375; 4,961,738; 4,958,932; 4,949,716; 4,896,941; 4,862,874; 4,850,371; 4,846,153; 4,819,664; 4,784,133; 4,742,819; 4,716,896; 4,567,882; 4,453,545; 4,468,216; 4,327,721; 4,327,720; 4,041,936; 3,913,568 3,866,599; 3,776,222; 3,677,262; 3,669,098; 3,498,286; 3,322,126; EP 1078601, WO 01/13908, WO 01/13839, WO 01/10314, WO 00/62699, WO 00/51510, WO 00/03642, WO 99/64109, WO 99/34741, WO 99/01076, WO 98/44854, WO 95/33506, and WO 92/10971.
WO 99/01076 describes devices and methods for reducing the size of lung tissue by applying heat energy to shrink collagen in the tissue. In one embodiment, air may be removed from a bleb in the lung to reduce its size. Air passages to the bleb may then be sealed, e.g., by heating, to fix the size of the bleb. WO 98/49191 describes a plug-like device for placement in a lung air passage to isolate a region of lung tissue, where air is not removed from the tissue prior to plugging. WO 98/48706 describes the use of surfactants in lung lavage for treating respiratory distress syndrome.
Lung volume reduction surgery is described in many publications, including Becker et al. (1998) Am. J. Respir. Crit. Care Med. 157:1593-1599; Criner et al. (1998) Am. J. Respir. Crit. Care Med. 157:1578-1585; Kotloff et al. (1998) Chest 113:890-895; and Ojo et al. (1997) Chest 112:1494-1500.
The use of mucolytic agents for clearing lung obstructions is described in Sclafani (1999) AARC Times, January, 69-97. Use of a balloon-cuffed bronchofiberscope to reinflate a lung segment suffering from refractory atelectasis is described in Harada et al. (1983) Chest 84:725-728.